Shock-responsive inertia mechanism



me 24, 1958 Y J.A. CHAMBERLIN ETAL 2,839,947 /v /f SHOCK-RESPONSIVE INERTIA MECHANISM James A. Chamberlin,

Alva 1 ,.Svveet,

T heir Attorrweg.

Y 2,839,947` SHOCK-RusrcNslvE INERTIA MECHANISMv James Chamberlin and Alva L. Sweet, Schenectady,YV N. -Y., assignors to General Electric Company, 4a cor-v poration of New, York n v Application January 3, 1956, S'ei'ial No. 556,956

8` claims. ,Y (ci. 'I4-521) Our invention relates to shock-responsive inertia mechanism, and particularly tofine'rtia mechanism for shock#y mon use have an operating mechanism of this type; forexample, the' tripping mechanism of automatic circuit breakers and .the operatingmechanism of circuit protective relays or the like thatfare intended normally to respond only to abnormal circuit conditions but areliable to operate falsely under shock conditions. In some'service the sock-responsive characteristic of such an automatic operating mechanism may be of utmost importance; Thus, to be acceptable for some critical installations, as, for example, on naval vessels and the like, any automatic device of the character indicated is required successfully to pass certain speciied yvery severe shock tests. "Also, any shockproong mechanism embodied in such device must not vary the sensitivity of response to the intendedabnormalcondition, and` furthermore, must be self-restoring after the shocksubsides, so as not to interfere withthe subsequentnormal automatic operation of the device.

As shock vibrations or oscillations may originate from diverse directions, the operating mechanism of an auto-4 matic device under shock test mustbe capable of withstanding the specified severe shock appliedy separately in the three principal x, y,z coordinate directions. Thus, the device may successfully withstand the specified severe test shock applied in a certain direction, without false operation, but -ail when the specied test shock is applied in some more vulnerable directions. Y

Various forms of shockproong mechanism have been proposed heretofore, and some have been used to some extent. But generally, their complications in structure, diiculties of application due to increased space requirement, as well as their apparent lack of effectiveness upon a severe shock in some vulnerable directions, still leave much to be desired. Y

Hence, one of the principal objects of the present invention is to provide an improved compact and simplified form of shock-responsive inertia mechanism that can be easily applied to bias a pivoted or rotatable operating member of an operating device to rotate in a predetermined nonoperating direction in response to shock in the most vulnerable directions, and stillproduce negligible interference with the normal operation of the member.

Another object is to provide an improved direction compensated shockproong mechanism having a pair' aired Safes Patent y(fm-lc@ directions, yand coordinated so as jointly to cooperate` l ineffectively shockproong the operating mechanismiof. device under shock applied in all required an automatic directions. Y Y

In some respects, the present invention .provides improvements upon theV pendulum type of shock-responsive` mechanism, disclosed and claimed in the Favre Patent.

2,467,200 thatk is assigned to theassignee of the'present invention. pendulum `weight that is supported for shock produced gyratory or limited universal tilting movement'in diverse directions from anl axis 'that is shown tilted withgrespect.

tothe axis of the trip-shaft of a circuit breaker. A

blocking member lisV rendered elfective upon a sutlicient.V

gyratory or limited tilting l'movement of the pendulum weight in any direction for blocking the rotation'of the trip-shaft 'of the'circuit breaker in the operating direction. However, itis often difficult to iindsucient spaceV to accommodate a shock-responsive mechanism such as. disclosed in therFavrelpatent. Moreover, unless properly oriented, the Y'Favre pendulum weight might fail to tilt or gyrate suiciently in response to a shock applied in somegvulnerable directions, Afor example, a shock applied in either ldirection along the gyratory axis'ofV-tl-ie pendulum weightj f t Such possible difficulties may be eectivelyovercome in accordance rwith `the present inventionV by providing improved means4 for shockproong a rotatable member subject to shock comprising a relatively movable-inertiaV element Y normally in shock-transmitting relationv withr the rotatablememberon one side of the axis thereof.V y Such shock-transmitting relation will produce a so-called bile liard ballyaction when the rotatable ,member is subject to the rotatable member on the other side ofthe axis so. as Vto extendV across the axis. Consequently, whenV ay suicient shockk is transmitted from the rotatable member'to the relativelymovableinertia element Vto propel the .inertia elementrapidly away from the rotatable,

member, the tension-transmitting connection thatv is 'attached tothe rotatable member onthe other side yof the axis becomes -elective to' transmit aV tension force that will biasthe rotatable memberbto. rotate in .the .samel predeterminedinonLoperating direction. Furthermore,

whenV the tensinltransmitting connection isfin tlie'form` of a light strip Yspring',1the relatively movable'inertia elef mentmay act like Va vpendulum and oscillate into and outl ofcontactrwith the rotatable member in lresponse to'fa v eryjsevere shock. But no matter inwhich directiontherelavtively movable inertia pendulum element is mov-f` ing,',tlieresultant.alternate impact or tension force always tends' to bias. the rotatable Ymember inthe predeterrninedv nonoperating direction with a force that .willV increase asfthe intensity of the Vshock increases. vBut normally ,when the shock Vsubsides,the inertia 'element willuthen moverjointly with the rotatablememberand hence impose negligible interferen-cewith the sensitivity. In casethe'operating mechanism of an automatic def` vice is designed vsethatr it is vulnerable to shock only'in some predominan'tdirfections, then the improved Ioscil-- lating pendulum'ine'rti element of the present in'i'fe'ntion may `'be -applied VYto effectively shockproof such'device,`

u 2,839,947 -n e 1,. Patented June This'fFavre patent discloses an inverted.,v

However,` the most effective over-al1 shoclrprootingV forall directions may be obtained by' providing a 'shockprooting mechanism including a pair of relatively movable inertia elements, diversely mounted and oriented so that one can operate on the tilting pendulum blocking principle of the Favre patent and the other on the billiard ball double-action'biasing principle provided by thepresent invention, sincewthe 'two inertia elementscan then cooperate on diverselyl .oriented axes ,so .as to: be selectively responsive to shock in any direction. In this way each .canaugment as rfar as 'possible the effectiveness of the other, to produce the maximum *shockproofing of the device.

sThe vimproved operating principles and advantages provided by the4 present invention :will be more fully appreciated by `referring to the following detailed specilication, taken in `conjunction withthe accompanying drawings, wherein Fig. l is a side view, partly. broken away, of a typical three-phase motor starting switch unit having theV improved shock responsive inertia mechanismo'f the present invention embodied therein Yfor shockproong purposes. unit shown iin Fig. 1. Fig. 3 is a side view of the tripfree snap action manual and automatic overload contact operating mechanism removed from the switch unit with certain parts broken away in order moreV clearly to revea'l `the details of the automatic tripping and shockproofng elements. Fig. 4'is'a cross-sectional view 0n the line A4-4I of Fig. ltshowing more clearly the operating relation of the overload responsive bimetal elements and shockproong elements `with the rotatable' tripping member.

Innthe` typical form `shown in Fig. 1, the three-phase manualand automatic overload protective motor starting switch unit comprises a generally rectangular molded casing having threey line terminals 11 mounted in alignment `at one end thereof and three motor connection terminals 12 similarly mounted at the other end thereof. A well-known form of trip-free manual and automatic overload snap action contact-operating mechanism indicated generally by the numeral 13 in Fig. 3 is 4mounted in a central recess formed in the molded cas# ing 10 and staked in position by the riveted over feet 14. This mechanism isprovided-with an operatingY and reset lever 15 that maybe engaged by a sliding operating handle 16 so as to operatethe overcenter spring snap action toggle mechanism4V to `move the contact-operating arm 17 between the on position in which it is shown in Fig. 3 and the otlfr'V position indicated by the dotted lines when the operating lever 15 is4 moved in opposite directions. The particular structure of the overcenter toggle switch operating mechanism 13 forms no part of thepresent invention and hence is not shown in detail. i

However, it may benoted that the operating'arm 17 extends through an` opening in the sliding insulating barrier 18 which carries three bridging contacts 19,

aligned in a row, into and out of circuit closing engage-V pair of contacts 20 is electrically connected `to the outer one of the Aline terminals 11, and the other contact20 Fig. 2 is an end view of the ,switch tripping of the contact operating mechanism 13 in the following manner.

As may be seen in the broken away portion of Fig. 3, the rotatable tripping control member 28 is pivotally mounted by means of the pin 30 that rotates in suitable bearing holes formed in the spaced apart parallel side plates 31 and 32 of the operating mechanism 13. The headed trip nger 33 is secured by pin 30 in interlocking relation with the rotatable control member 28 to move as a unit therewith to engage or disengage the rounded cam end of the trip finger 33 with the upper edge of the slot 34 Vformedrin the latch member 35 that is pivotally mounted onthe pin 36. As long as the cam end of trip tinger 33' remains in engagement with the upper edge of the slot 34 as shown in Fig. 3, the bent-over end 35a of latch 35 will be locked in engagement with the roller 37 that is carried at the end of the toggle link element 38 of the operating mechanism 13 having the spring 39 thrown each way overcenter as the operating lever 15 is oppositely rotated about its pivotal bearings 40.

The rotatable control member 28 is biased by spring 43 f' to the position 4in which it is shown in Fig. 3, wherein is electrically connectedV to a nut insert '21 for the `moun'ty ing screwj22 for .one terminal of the removable electric overload heater 23.` The other terminal of the heater 23 is removably connected by means of the screw 24 to the conductingbracket 25 extending from the motor terminalscrew 12. The bracket 25 carries a bimetal ele` ment ,26 `that is heated' bythe heater 23 to provide an inverse time tripping characteristic. In order to calibrate the time "delay overload .trippingresponse the bimetal eleinent`26fis Aadjustat'jly mounted to vary the distanceY between its free end 26a and the insulating pin 27 pro-v jectingfrom the pivotally mounted or rotatable operatfV ing memberz `that is constructed to Vcontrolthe automatic the upper end 47 rests vagainst the molded housing 10 and the trip `finger 33 is in holding engagementv with the upper edge of the slot 34. The spring 43 engages with the disk member 44 having a hub that freely slides along the pin 45 extending from the supporting plate 46 secured betweenV the side plates 31 and 32 0f the operating mechamsm.

ln order to shockproof the operating mechanism 13 in accordance with the present invention a pair of relatively movable inertia elements 50 and 51 are diversely oriented with respect to the axis of the rotatable member 28 and coordinated so as jointly to cooperate in controlling the movement of the rotatable member in the clockwise or operating direction under shock conditions The inertia element 50 as shown is of a generally bell-shaped form with the pin 45 extending through an enlarged opening in the closed end of the bell so as to permit limited gyratory or tilting movement thereof in any direction in response to shock. Normally the bell-shaped inertia element 50 is biased by the spring 43 into contact with the supporting plate 46 with the rim of the bell substantially'equidistant from the xed pin 45 as shown in Fig. 3. In this way the-normal axis of the swinging or pendulum like inertia element 50 is disposed perpendicular to-a plane passing Vthrough the axis of pin 30 upon which the member 28 is rotatably mounted.

rlhe `inertia element 51 is supported by a-relatively light stripfspring'52 having one end secured to the rotat# able controlV member y28 by suitable rivets 53Yon one side of `the axis 30 so that the inertia element 51 is lightly biased into shock-transmitting contact with the rotatable member 28'on the other side of the axis 30 as shown in Fig.-3.

' YOperation Under normal conditions when there is no shock, the bell-shaped inertia element 50 will remain stationary in the position in which it is shown in Fig. 3, and the spring rnerrrber'351.0 rotate n the counterclockwse direction to "release the roller 37. Thereupon the toggle mechanism willoperate-the contact operatingarm 17 from the fon position to the oli position with a snap action .to disengage -the bridging contacts 19 'from the stationary` contacts 20 and thereby interrupt the circuit. When the bimetal element 26 has cooled, so as to disengage the pin 27, all the operating parts maybe reset into their initial positions by means of the operating and reset lever 15.

Whenever the operating mechanism 13 is subjected to shock, unless prevented by one or both of the inertia elements 50 and 51, the rotatable control member 28 may tend to rotate in the operating direction an amount depending upon the severity of the shock. Thus, in the absence of the inertia elements 50 and 51, the shock produced rotation of control member 28 might become suicient to carry the cam end of the finger 33 over the edge of the slot 34 and thereby produce false operation of the mechanism 13 to open the circuit controlling contacts 19. This might also result from vibration of the free end of the birnetal element 26 under severe shock conditions except for the shockproofing action of the inertia elements 50 and 51.

In response to shock, the bell-shaped inertia element 50 can gyrate or tilt in any direction so as to bring the rim of the member into position to block the disk 44 and thereby prevent suicient rotation of the rotatable member 28 in the operating direction to disengage the cam end of nger 33 from the edge of slot 34.

Also, in response to shock the inertia element 51 due to the so-called billiard ball action when the shock is transmitted either through the bimetal element Z6 or latch 33, or from case 10 or from the side frames 31 and 32 through the pivot pin 30 of the rotatable control member 28, may rapidly propel the inertia element 51 either towards or away from the rotatable member 28. In the rst case, the transmitted shock will directly bias the control member 28 in the nonoperating direction. In the second case the resulting relative movement of the inertia element 51 will transmit tension through the spring 52 to its point of attachment on the other side of the axis 30 of the rotatable member 28. Consequently, the force exerted by the transmitted tension will serve to bias the rotatable control member 2.8 to rotate in the nonoperating direction. Upon any rebound of inertia element 51, the re-engagement thereof with the rotatable member 28 on the other side of the axis will likewise tend to bias the control member 28 to rotate in the nonoperating direction. Thus, upon any relative movement of inertia element 51 in either direction, the biasing action is always in the same direction.

Due to the diverse orientation of the relative movements of the inertia elements 50 and S1, each can respond most effectively to shock applied in certain directions and in this way the pair of elements can be coordinated to cooperate in most eifectively shockproofing the operating mechanism 13 against test shocks applied in all required directions. However, if desired, the inertia element 51 may be used alone in any case Where it is only necessary to provide for shockproong a rotatable control member in the most vulnerable directions.

Although in accordance with the provisions of the patent statutes this invention is described as embodied in concrete form and the principle of the invention has been described together with the best manner in which it is now contemplated applying that principle, it will be understood that the description is merely illustrative and that alterations and-modications will readily occur to persons skilled in the art without vdeparting from the true spirit of the invention or from the scope of the annexed claims.

What we claim as new and desire to secure by Letters Patent of the United States, is:

l. In a device having a rotatable member subject to shock, means including a relatively movable inertia element normally in shock-transmitting relation with the rotatable member on one side of the axis thereof and having a tension-transmitting connection attached to the rotatable member on the other side of said axis to bias the member to rotate in a predetermined direction upon 6 a sudden relative movement of the inertia element in response to shock.

2. A device having in combination a rotatable member` subject to shock, a relatively movable inertia element, means for normally mounting the inertia element to rotate jointly with the rotatable member in shock-transmitting contact therewith on one side of the axis, thereof, and a tension-transmitting connection extending from the inertia element and attached to the rotatable member on the other side of said axis to bias the member to rotate in a predetermined direction upon a suddent relative movement of the inertia element in response to shock.

3. In combination, a device having a reversely rotatable member subject to shock, and means including an oscillatable inertia element having a shock-transmitting connection with the rotatable member on one side of the axis thereof and provided with a tension-transmitting connection to themember on the opposite side of the said axis for biasing the member to rotate in a predetermined direction upon oscillation of the inertia element due to shock.

4. A device having a rotatable member subject to shock and having a relatively movable inertia pendulum attached to the rotatable member on one side of the axis thereof to extend normally into shock transmitting contact with'the member on the other side of said axis for biasing the member to rotate in a predetermined direction upon relative movement of the inertia pendulum due to shock.

5. In combination, an automatic device having a rotatable operating Vmember subject to shock, conditionresponsive means for rotating the member in the operating direction, an inertia element having a supporting spring attached to the rotatable member on one side of the axis thereof to support the inertia element in shocktransmitting contact with the member on the other side of said axis to bias the member 'to rotate in the nonoperating direction upon a sudden relative movement of the inertia element in response to shock.

6. In a device having a rotatable member subject to shock, a relatively movable inertia element having a supporting spring attached to the rotatable member on one side of its axis of rotation and extending transverse to said axis to support said inertia element in contact with said member on the other side of said axis to bias said member to rotate in a predetermined direction upon a sudden relative movement of the inertia element in response to shock.

7. In combination, a device subject to shock and having a rotatable operating member and means for shock-proofing the device including a pair of relatively movable inertia elements, one of said elements having mounting means for supporting the one inertia element on the device for shock produced limited universal tilting in diverse directions from an axis extending transverse the axis of the rota-table member, and blocking means rendered effective upon the limited tilting movement of the one element in each direction for blocking the rotation of the operating member in the operating direction, and the other of said inertia elements having a tensiontransmitting connection attached to the rotatable member on one side of the axis thereof for supporting the other inertia element in shock-transmitting contact with the rotatable member on the other side of said axis of said rotatable member to bias saidmember to rotate in the nonoperating direction upon a sudden relative movement of the other inertia element in response to shock.

8. In combination, a device subject to shock and having a rotatable member and means for shockproofmg the device including a pair of diversely oriented relatively Y movable inertia elements, one having means for mounting the one element on the device for shock-produced, substantially universal, tilting movement from an axis normal to a plane through the axis ofthe rotatable mem- 7 E ber, and having means effective upon shock-produced rotate in 'the nonoperating `direction upon shock-proltilting movement of the one element in substantially any duced relative movement of the other inertia element. direction-for blocking-movement of the rotatable member j in the operating direction, and the other relatively mov- References Citedinthe file of this patent able inertia element havin a tension-transmittin su g g P 5 UNITED STATES PATENTS port attached `to the `rotatable member and extending transverse the axis thereof for biasing the member to 2,467,200 Favre Apr. l2, 1949 

